crypto/libressl/crypto/rsa/rsa_gen.c

   1 /* $OpenBSD: rsa_gen.c,v 1.17 2015/02/09 15:49:22 jsing Exp $ */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59
  60 /* NB: these functions have been "upgraded", the deprecated versions (which are
  61  * compatibility wrappers using these functions) are in rsa_depr.c.
  62  * - Geoff
  63  */
  64
  65 #include <stdio.h>
  66 #include <time.h>
  67
  68 #include <openssl/bn.h>
  69 #include <openssl/err.h>
  70 #include <openssl/rsa.h>
  71
  72 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);
  73
  74 /*
  75  * NB: this wrapper would normally be placed in rsa_lib.c and the static
  76  * implementation would probably be in rsa_eay.c. Nonetheless, is kept here so
  77  * that we don't introduce a new linker dependency. Eg. any application that
  78  * wasn't previously linking object code related to key-generation won't have to
  79  * now just because key-generation is part of RSA_METHOD.
  80  */
  81 int
  82 RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
  83 {
  84         if (rsa->meth->rsa_keygen)
  85                 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
  86         return rsa_builtin_keygen(rsa, bits, e_value, cb);
  87 }
  88
  89 static int
  90 rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
  91 {
  92         BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
  93         BIGNUM pr0, d, p;
  94         int bitsp, bitsq, ok = -1, n = 0;
  95         BN_CTX *ctx = NULL;
  96
  97         ctx = BN_CTX_new();
  98         if (ctx == NULL)
  99                 goto err;
 100         BN_CTX_start(ctx);
 101         if ((r0 = BN_CTX_get(ctx)) == NULL)
 102                 goto err;
 103         if ((r1 = BN_CTX_get(ctx)) == NULL)
 104                 goto err;
 105         if ((r2 = BN_CTX_get(ctx)) == NULL)
 106                 goto err;
 107         if ((r3 = BN_CTX_get(ctx)) == NULL)
 108                 goto err;
 109
 110         bitsp = (bits + 1) / 2;
 111         bitsq = bits - bitsp;
 112
 113         /* We need the RSA components non-NULL */
 114         if (!rsa->n && ((rsa->n = BN_new()) == NULL))
 115                 goto err;
 116         if (!rsa->d && ((rsa->d = BN_new()) == NULL))
 117                 goto err;
 118         if (!rsa->e && ((rsa->e = BN_new()) == NULL))
 119                 goto err;
 120         if (!rsa->p && ((rsa->p = BN_new()) == NULL))
 121                 goto err;
 122         if (!rsa->q && ((rsa->q = BN_new()) == NULL))
 123                 goto err;
 124         if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
 125                 goto err;
 126         if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
 127                 goto err;
 128         if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
 129                 goto err;
 130
 131         BN_copy(rsa->e, e_value);
 132
 133         /* generate p and q */
 134         for (;;) {
 135                 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
 136                         goto err;
 137                 if (!BN_sub(r2, rsa->p, BN_value_one()))
 138                         goto err;
 139                 if (!BN_gcd(r1, r2, rsa->e, ctx))
 140                         goto err;
 141                 if (BN_is_one(r1))
 142                         break;
 143                 if (!BN_GENCB_call(cb, 2, n++))
 144                         goto err;
 145         }
 146         if (!BN_GENCB_call(cb, 3, 0))
 147                 goto err;
 148         for (;;) {
 149                 /*
 150                  * When generating ridiculously small keys, we can get stuck
 151                  * continually regenerating the same prime values. Check for
 152                  * this and bail if it happens 3 times.
 153                  */
 154                 unsigned int degenerate = 0;
 155                 do {
 156                         if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL,
 157                             cb))
 158                                 goto err;
 159                 } while (BN_cmp(rsa->p, rsa->q) == 0 &&
 160                     ++degenerate < 3);
 161                 if (degenerate == 3) {
 162                         ok = 0; /* we set our own err */
 163                         RSAerr(RSA_F_RSA_BUILTIN_KEYGEN,
 164                             RSA_R_KEY_SIZE_TOO_SMALL);
 165                         goto err;
 166                 }
 167                 if (!BN_sub(r2, rsa->q, BN_value_one()))
 168                         goto err;
 169                 if (!BN_gcd(r1, r2, rsa->e, ctx))
 170                         goto err;
 171                 if (BN_is_one(r1))
 172                         break;
 173                 if (!BN_GENCB_call(cb, 2, n++))
 174                         goto err;
 175         }
 176         if (!BN_GENCB_call(cb, 3, 1))
 177                 goto err;
 178         if (BN_cmp(rsa->p, rsa->q) < 0) {
 179                 tmp = rsa->p;
 180                 rsa->p = rsa->q;
 181                 rsa->q = tmp;
 182         }
 183
 184         /* calculate n */
 185         if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
 186                 goto err;
 187
 188         /* calculate d */
 189         if (!BN_sub(r1, rsa->p, BN_value_one()))        /* p-1 */
 190                 goto err;
 191         if (!BN_sub(r2, rsa->q, BN_value_one()))        /* q-1 */
 192                 goto err;
 193         if (!BN_mul(r0, r1, r2, ctx))                   /* (p-1)(q-1) */
 194                 goto err;
 195
 196         BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME);
 197
 198         if (!BN_mod_inverse(rsa->d, rsa->e, &pr0, ctx)) /* d */
 199                 goto err;
 200
 201         /* set up d for correct BN_FLG_CONSTTIME flag */
 202         BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
 203
 204         /* calculate d mod (p-1) */
 205         if (!BN_mod(rsa->dmp1, &d, r1, ctx))
 206                 goto err;
 207
 208         /* calculate d mod (q-1) */
 209         if (!BN_mod(rsa->dmq1, &d, r2, ctx))
 210                 goto err;
 211
 212         /* calculate inverse of q mod p */
 213         BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME);
 214         if (!BN_mod_inverse(rsa->iqmp, rsa->q, &p, ctx))
 215                 goto err;
 216
 217         ok = 1;
 218 err:
 219         if (ok == -1) {
 220                 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
 221                 ok = 0;
 222         }
 223         if (ctx != NULL) {
 224                 BN_CTX_end(ctx);
 225                 BN_CTX_free(ctx);
 226         }
 227
 228         return ok;
 229 }